export function draw(show_num) {
  let canvas = document.getElementsByClassName('search_canvas')[0];
  let canvas_width = '90';
  let canvas_height = '32';
  let context = canvas.getContext('2d'); //获取到canvas画图的环境，演员表演的舞台
  canvas.width = canvas_width;
  canvas.height = canvas_height;
  let sCode =
    'a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0';
  let aCode = sCode.split(',');
  let aLength = aCode.length; //获取到数组的长度
  for (let i = 0; i < 4; i++) {
    //这里的for循环可以控制验证码位数（如果想显示6位数，4改成6即可）
    let j = Math.floor(Math.random() * aLength); //获取到随机的索引值
    // let deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
    //  let deg = Math.random() - 0.5;  产生一个随机弧度
    let txt = aCode[j]; //得到随机的一个内容
    show_num[i] = txt.toLowerCase();
    let x = 13 + i * 20; //文字在canvas上的x坐标
    let y = 20; //文字在canvas上的y坐标
    context.font = 'bold 12px Alibaba PuHuiTi';
    context.translate(x, y);
    context.fillStyle = '#fff';
    context.fillText(txt, 0, 0);
    context.translate(-x, -y);
  }
  return show_num;
}
